J/MNRAS/468/L6 Quasars narrow absorption lines from SDSS (Lu+, 2017)
Evidence for photoionization-driven variability in narrow absorption lines.
Lu W.-J., Lin Y.-R., Qin Y.-P., Huang W.-R., Pan C.-J., Huang H.-Y.,
Yao M., Nong W.-J., Yao Z.-K., Lu M.-M., Pan D.-S., Huang H.-Q., Han Q.-L.
<Mon. Not. R. Astron. Soc., 468, L6 (2017)>
=2017MNRAS.468L...6L 2017MNRAS.468L...6L (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Equivalent widths
Keywords: galaxies: active - quasars: absorption lines - quasars: general
Abstract:
In this Letter, we report the discovery of a strong correlation
between the variability of narrow absorption lines (NALs) and the
ionizing continuum from a two-epoch spectral sample of 40 quasars
containing 52 variable CIV λλ1548, 1551 absorption
doublets. According to the concordance index, this sample is
classified into two subsamples. Subsample I shows an anti-correlation
between the variations of absorption lines and the continuum, while
Subsample II exhibits a positive correlation. These results imply that
these variable CIV λλ1548, 1551 absorption doublets are
intrinsic to the corresponding quasars and that their variations are
caused primarily by the fluctuations of the ionizing continuum. Based
on our analysis, we propose that there might be two kinds of
absorption gas: one that is very sensitive to the continuum
variations, and another that is not. In addition, we suggest that in
many cases the emergence or disappearance of NALs is caused by
fluctuations of the ionizing continuum.
Description:
We have studied the correlation between the NAL variability and the
continuum variability using a sample of two-epoch SDSS spectra of 40
quasars with 52 variable narrow-absorption systems. We analysed
quantitatively the variability amplitude of EWs of CIV absorption
lines and that of the continuum flux and found a significant
correlation between them. As hinted at by the statistical results, we
propose that the changes of the CIV λλ1548, 1551
absorption doublets in our sample are driven mainly by the
fluctuations of the ionizing continuum.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 116 52 CIV absorption systems and the continuum data
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See also:
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/MNRAS/450/3904 : Quasars narrow absorption lines from SDSS (Chen+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS SDSS identifier, HHMMSS.ss+DDMMSS.s
21- 26 F6.4 --- zem Redshift derived from emission lines (1)
29- 34 F6.4 --- zabs Redshift derived from absorption
lines (2)
37- 41 F5.2 10-19W/m2/nm Fcont1 Flux of the pseudo-continuum for the
earlier epoch (3)
44- 47 F4.2 10-19W/m2/nm e_Fcont1 Error of Fcont1
50- 54 F5.2 10-19W/m2/nm Fcont2 Flux of the pseudo-continuum for the
later epoch (3)
57- 60 F4.2 10-19W/m2/nm e_Fcont2 Error of Fcont2
63- 67 F5.2 --- DFcont Flux variability amplitude
70- 73 F4.2 --- e_DFcont Error of flux variability amplitude
76- 80 F5.2 --- DEW48 Equivalent widths variability amplitude
of C IV λ1548
83- 86 F4.2 --- e_DEW48 Error of equivalent widths variability
amplitude
89- 93 F5.2 --- DEW51 Equivalent widths variability amplitude
of C IV λ1551
96- 99 F4.2 --- e_DEW51 Error of equivalent widths variability
amplitude
102-103 I2 --- Index [-1/1]? The concordance index (4)
106-116 A11 --- Note Change of the absorption line (2)
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Note (1): Following Chen et al. (2015, J/MNRAS/450/3904), the value of zem is
taken from Hewett & Wild (2010, Cat. J/MNRAS/405/2302).
Note (2): The value of zabs and the contents of 'Note' are directly taken from
Chen et al. (2015, J/MNRAS/450/3904).
Note (3): The values of Fnoise1 and Fnoise2 are measured in units of
10-17erg/cm2/s/Å.
Note (4): concordance index as follows:
+1 = for cases in which both the absorption line and the continuum become
stronger or both of them become weaker
-1 = when they vary in the opposite way
0 = when the continuum has no significant variation
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Mar-2020